Singular matrix error for CPU workflow

[isce-framework]

Singular matrix error for CPU workflow

[scottstanie]

This was happening here from one eigenvalue that was -2e-7:

ipdb> np.linalg.eigh(Gamma[55, 1107] * C_arrays[55, 1107])[0]
array([-2.1234169e-07,  5.1951128e-01,  9.0359849e-01,  9.2329526e-01,
        9.5432651e-01,  9.8514080e-01,  1.0000000e+00,  1.0000000e+00,
        1.0000000e+00,  1.0000000e+00,  1.0000000e+00,  1.0000000e+00,
        1.0000000e+00,  1.0000000e+00,  1.0172563e+00,  1.0392334e+00,
        1.0573467e+00,  1.1158751e+00,  2.4844165e+00], dtype=float32)

In the test run of the fix in #44, the error goes away.